Mechanical brake systems, including those brake systems in which the force is applied to the mechanical components by means of pneumatic pressure, i.e., air brakes, are generally of the type in which brake shoes are pressed outwardly against a brake drum. Disc brake systems, on the other hand, generally include hydraulically actuated pistons and cylinders, with the pistons being forced outwardly to press the brake pads against the disc face by means of hydraulic pressure.
Additionally, although most hydraulic brake systems include some type of self-adjusting mechanism for compensation for brake pad wear, mechanical brake systems, including those actuated by air pressure, generally do not include such self-adjusting features.